/**
* Handle a IP address conflict after an ARP conflict detection
*/
static void
autoip_handle_arp_conflict(struct netif *netif)
{
/* Somehow detect if we are defending or retreating */
unsigned char defend = 1; /* tbd */
if (defend) {
if (netif->autoip->lastconflict > 0) {
/* retreat, there was a conflicting ARP in the last
* DEFEND_INTERVAL seconds
*/
LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
("autoip_handle_arp_conflict(): we are defending, but in DEFEND_INTERVAL, retreating\n"));
/* TODO: close all TCP sessions */
autoip_restart(netif);
} else {
LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
("autoip_handle_arp_conflict(): we are defend, send ARP Announce\n"));
autoip_arp_announce(netif);
netif->autoip->lastconflict = DEFEND_INTERVAL * AUTOIP_TICKS_PER_SECOND;
}
} else {
LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
("autoip_handle_arp_conflict(): we do not defend, retreating\n"));
/* TODO: close all TCP sessions */
autoip_restart(netif);
}
}
/**
* Handles every incoming ARP Packet, called by etharp_arp_input.
*
* @param netif network interface to use for autoip processing
* @param hdr Incoming ARP packet
*/
void
autoip_arp_reply(struct netif *netif, struct etharp_hdr *hdr)
{
LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_arp_reply()\n"));
if ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) {
/* when ip.src == llipaddr && hw.src != netif->hwaddr
*
* when probing ip.dst == llipaddr && hw.src != netif->hwaddr
* we have a conflict and must solve it
*/
ip_addr_t sipaddr, dipaddr;
struct eth_addr netifaddr;
ETHADDR16_COPY(netifaddr.addr, netif->hwaddr);
/* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
* structure packing (not using structure copy which breaks strict-aliasing rules).
*/
IPADDR2_COPY(&sipaddr, &hdr->sipaddr);
IPADDR2_COPY(&dipaddr, &hdr->dipaddr);
if ((netif->autoip->state == AUTOIP_STATE_PROBING) ||
((netif->autoip->state == AUTOIP_STATE_ANNOUNCING) &&
(netif->autoip->sent_num == 0))) {
/* RFC 3927 Section 2.2.1:
* from beginning to after ANNOUNCE_WAIT
* seconds we have a conflict if
* ip.src == llipaddr OR
* ip.dst == llipaddr && hw.src != own hwaddr
*/
if ((ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr)) ||
(ip_addr_cmp(&dipaddr, &netif->autoip->llipaddr) &&
!eth_addr_cmp(&netifaddr, &hdr->shwaddr))) {
LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | LWIP_DBG_LEVEL_WARNING,
("autoip_arp_reply(): Probe Conflict detected\n"));
/* Clear stored lladdr in case of conflict. As device should now
* re-probe conflicted address. */
memset(&prev_llipaddr, 0, sizeof(ip_addr_t));
autoip_restart(netif);
}
} else {
/* RFC 3927 Section 2.5:
* in any state we have a conflict if
* ip.src == llipaddr && hw.src != own hwaddr
*/
if (ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr) &&
!eth_addr_cmp(&netifaddr, &hdr->shwaddr)) {
LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | LWIP_DBG_LEVEL_WARNING,
("autoip_arp_reply(): Conflicting ARP-Packet detected\n"));
/* Clear stored lladdr in case of conflict. As device should now
* re-probe conflicted address.
* Clear stored address only if it was not announced */
if (netif->autoip->state != AUTOIP_STATE_BOUND)
memset(&prev_llipaddr, 0, sizeof(ip_addr_t));
autoip_handle_arp_conflict(netif);
}
}
}
}